It is known to provide free-wheeling arrangements within the drive train of automotive vehicles in which engagement or disengagement of a free-wheeling feature is controlled in dependence on operation of the accelerator and the brake pedal, respectively, by the vehicle operator. Such a drive system is described, for example, in the referenced U.S. Pat. No. 4,084,672.
The referenced application Ser. No. 06/398,349, filed July 15, 1982, now U.S. Pat. No. 4,509,628 JUNGINGER, entitled "VEHICULAR DRIVE SYSTEM", assigned to the assignee of the present application, describes a system in which signals controlling the free-wheeling transmission are averaged with respect to time in order to control engagement and disengagement of the free-wheeling feature independent of short-time or transient conditions, so that the free-wheeling feature is engaged only if it is actually desired, and if it is economically appropriate.
It has been found that engagement and disengagement of a free-wheeling feature in transmissions may, under some operating conditions, cause shifting or gear switching jolts, which are undesirable for smooth vehicle operation, and detract from operator and passenger comfort in the operation of the vehicle.
Under free-wheeling operation, the transmission gears, and the transmission gear input shaft coupled thereto will operate at a speed which is higher than engine speed since, it is assumed, that under freewheeling operation the engine will be under idling condition. To establish synchronism and to reduce coupling jolts, the automatic system, therefore, provides fuel to the engine to accelerate the engine such that its output shaft will approach and reach synchronism with the input shaft of the transmission. As synchronism is obtained, the automatic system loses control, disabling of free-wheeling, normally, is commanded by operation of the brake, so that the operator will not provide fuel for continuous engine operation at higher, that is, synchronous transmission speed. A coupling jolt may result due to the sudden transition of engine operation from accelerating mode to engine braking mode.